972 research outputs found
Extraocular muscle sampled volume in Graves' orbitopathy using 3-T fast spin-echo MRI with iterative decomposition of water and fat sequences
Abstract
Background: Current magnetic resonance imaging (MRI) techniques for measuring extraocular muscle (EOM) volume
enlargement are not ideally suited for routine follow-up of Graves’ ophthalmopathy (GO) because the difficulty of
segmenting the muscles at the tendon insertion complicates and lengthens the study protocol.
Purpose: To measure the EOM sampled volume (SV) and assess its correlation with proptosis.
Material and Methods: A total of 37 patients with newly diagnosed GO underwent 3-T MRI scanning with iterative
decomposition of water and fat (IDEAL) sequences with and without contrast enhancement. In each patient, the three
largest contiguous coronal cross-sectional areas (CSA) on the EOM slices were segmented using a polygon selection tool
and then summed to compute the EOM-SV. Proptosis was evaluated with the Hertel index (HI). The relationships
between the HI value and EOM-SV and between HI and EOM-CSA were compared and assessed with Pearson’s correlation
coefficient and the univariate regression coefficient. Inter-observer and intra-observer variability were
calculated.
Results: HI showed a stronger correlation with EOM-SV (P<0.001; r¼0.712, r2¼0.507) than with EOM-CSA
(P<0.001; r¼0.645 and r2¼0.329). The intraclass correlation coefficient indicated that the inter-observer agreement
was high (0.998). The standard deviation between repeated measurements was 1.9–5.3%.
Conclusion: IDEAL sequences allow for the measurement EOM-SV both on non-contrast and contrast-enhanced scans.
EOM-SV predicts proptosis more accurately than does EOM-CSA. The measurement of EOM-SV is practical and
reproducible. EOM-SV changes of 3.5–8.3% can be assumed to reflect true volume changes
Genetic and morphological studies of Trichosirocalus species introduced to North America, Australia and New Zealand for the biological control of thistles
Trichosirocalus horridus sensu lato has been used as a biological control agent of several invasive thistles (Carduus spp., Cirsium spp. and Onopordum spp.) since 1974. It has been recognized as a single species until 2002, when it was split into three species based on morphological characters: T. horridus, Trichosirocalus briesei and Trichosirocalus mortadelo, each purported to have different host plants. Because of this taxonomic change, uncertainty exists as to which species were released in various countries; furthermore, there appears to be some exceptions to the purported host plants of some of these species. To resolve these questions, we conducted an integrative taxonomic study of the T. horridus species complex using molecular genetic and morphological analyses of specimens from three continents. Both mitochondrial cytochrome c oxidase subunit I and nuclear elongation factor 1α markers clearly indicate that there are only two distinct species, T. horridus and T. briesei. Molecular evidence, morphological analysis and host plant associations support the synonymy of T. horridus (Panzer, 1801) and T. mortadelo Alonso-Zarazaga & Sánchez-Ruiz, 2002. We determine that T. horridus has been established in Canada, USA, New Zealand and Australia and that T. briesei is established in Australia. The former species was collected from Carduus, Cirsium and Onopordum spp. in the field, whereas the latter appears to be specific to Onopordum
How Much Does GenoGuard Really "Guard"? An Empirical Analysis of Long-Term Security for Genomic Data
Due to its hereditary nature, genomic data is not only linked to its owner but to that of close relatives as well. As a result, its sensitivity does not really degrade over time; in fact, the relevance of a genomic sequence is likely to be longer than the security provided by encryption. This prompts the need for specialized techniques providing long-term security for genomic data, yet the only available tool for this purpose is GenoGuard~\citehuang_genoguard:_2015. By relying on \em Honey Encryption, GenoGuard is secure against an adversary that can brute force all possible keys; i.e., whenever an attacker tries to decrypt using an incorrect password, she will obtain an incorrect but plausible looking decoy sequence. In this paper, we set to analyze the real-world security guarantees provided by GenoGuard; specifically, assess how much more information does access to a ciphertext encrypted using GenoGuard yield, compared to one that was not. Overall, we find that, if the adversary has access to side information in the form of partial information from the target sequence, the use of GenoGuard does appreciably increase her power in determining the rest of the sequence. We show that, in the case of a sequence encrypted using an easily guessable (low-entropy) password, the adversary is able to rule out most decoy sequences, and obtain the target sequence with just 2.5% of it available as side information. In the case of a harder-to-guess (high-entropy) password, we show that the adversary still obtains, on average, better accuracy in guessing the rest of the target sequences than using state-of-the-art genomic sequence inference methods, obtaining up to 15% improvement in accuracy
Measuring, Characterizing, and Detecting Facebook Like Farms
Social networks offer convenient ways to seamlessly reach out to large
audiences. In particular, Facebook pages are increasingly used by businesses,
brands, and organizations to connect with multitudes of users worldwide. As the
number of likes of a page has become a de-facto measure of its popularity and
profitability, an underground market of services artificially inflating page
likes, aka like farms, has emerged alongside Facebook's official targeted
advertising platform. Nonetheless, there is little work that systematically
analyzes Facebook pages' promotion methods. Aiming to fill this gap, we present
a honeypot-based comparative measurement study of page likes garnered via
Facebook advertising and from popular like farms. First, we analyze likes based
on demographic, temporal, and social characteristics, and find that some farms
seem to be operated by bots and do not really try to hide the nature of their
operations, while others follow a stealthier approach, mimicking regular users'
behavior. Next, we look at fraud detection algorithms currently deployed by
Facebook and show that they do not work well to detect stealthy farms which
spread likes over longer timespans and like popular pages to mimic regular
users. To overcome their limitations, we investigate the feasibility of
timeline-based detection of like farm accounts, focusing on characterizing
content generated by Facebook accounts on their timelines as an indicator of
genuine versus fake social activity. We analyze a range of features, grouped
into two main categories: lexical and non-lexical. We find that like farm
accounts tend to re-share content, use fewer words and poorer vocabulary, and
more often generate duplicate comments and likes compared to normal users.
Using relevant lexical and non-lexical features, we build a classifier to
detect like farms accounts that achieves precision higher than 99% and 93%
recall.Comment: To appear in ACM Transactions on Privacy and Security (TOPS
Characterizing Key Stakeholders in an Online Black-Hat Marketplace
Over the past few years, many black-hat marketplaces have emerged that
facilitate access to reputation manipulation services such as fake Facebook
likes, fraudulent search engine optimization (SEO), or bogus Amazon reviews. In
order to deploy effective technical and legal countermeasures, it is important
to understand how these black-hat marketplaces operate, shedding light on the
services they offer, who is selling, who is buying, what are they buying, who
is more successful, why are they successful, etc. Toward this goal, in this
paper, we present a detailed micro-economic analysis of a popular online
black-hat marketplace, namely, SEOClerks.com. As the site provides
non-anonymized transaction information, we set to analyze selling and buying
behavior of individual users, propose a strategy to identify key users, and
study their tactics as compared to other (non-key) users. We find that key
users: (1) are mostly located in Asian countries, (2) are focused more on
selling black-hat SEO services, (3) tend to list more lower priced services,
and (4) sometimes buy services from other sellers and then sell at higher
prices. Finally, we discuss the implications of our analysis with respect to
devising effective economic and legal intervention strategies against
marketplace operators and key users.Comment: 12th IEEE/APWG Symposium on Electronic Crime Research (eCrime 2017
Sensory Adaptation of Antennae and Sex Pheromone-Mediated Flight Behavior in Male Oriental Fruit Moths (Leptidoptera: Tortricidae) After Prolonged Exposure to Single and Tertiary Blends of Synthetic Sex Pheromone
Sensory adaptation has been measured in the antennae of male Grapholita molesta (Busck) after 15 min of exposure to its main pheromone compound (Z)-8-dodecen-1-yl acetate (Z8-12:OAc) at the aerial concentration of 1 ng/m(3) measured in orchards treated with pheromone for mating disruption. Exposing males to this aerial concentration of Z8-12:OAc for 15 min, however, had only a small effect on their ability to orientate by flight to virgin calling females in a flight tunnel. Experiments were undertaken to determine if exposure to the main pheromone compound in combination with the two biologically active minor compounds of this species, (E)-8-dodecen-1-yl acetate (E8-12:OAc) and (Z)-8-dodecen-1-ol (Z8-12:OH) would induce greater levels of sensory adaptation and have a greater effect on male sexual behavior. The exposure of male antennae to 0.5 g/m(3) air of one of the three pheromone compounds induced sensory adaptation to this compound and to the other two pheromone compounds demonstrating cross adaptation. Average percentage sensory adaptation to a pheromone compound was similar after 15 min of exposure to 1 ng/m(3) air of Z8-12:OAc, or to 1 ng/m(3) air of a 1:1:1 or 93:6:1 blend of Z8-12:OAc, E8-12:OAc, and Z8-12:OH. The exposure of males to 1 ng/m(3) air of Z8-12:OAc or the two ratios of Z8-12:OAc, E8-12:OAc, and Z8-12:OH for 15 min had no effect on their ability to orientate to a virgin calling female. The implications of these results for the operative mechanisms of sex pheromone-mediated mating disruption of this species are discussed
Comparison of local injection of methotrexate and linear salpingostomy in the conservative laparoscopic treatment of ectopic pregnancy
STUDY OBJECTIVE: To compare local injection of metothrexate (MTX) and linear salpingostomy in the conservative laparoscopic treatment of ectopic pregnancy. DESIGN: Prospective, nonrandomized study, July 1991 to May 1994. SETTING: Department of obstetrics and gynecology in a university hospital. PATIENTS: Fourteen women with unruptured ectopic pregnancies without documented fetal heart motion and size below 50 mm as measured by ultrasound. INTERVENTIONS: All 14 women underwent the laparoscopic treatment by either local injection of MTX or linear salpingostomy (7 patients each). MEASUREMENTS AND MAIN RESULTS: Both treatments were successful in all patients. Mean length of operation was 32 +/- 5 minutes (range 25-35 min) in the MTX group versus 67 +/- 15 minutes (range 50-90 min) in the salpingostomy group. Mean length of hospital stay was 2.7 days (range 1-5 days) and 1.7 days (range 1-3 days), respectively. No intraoperative complications occurred, and the postoperative course was uneventful in all women. Mean disappearance time of serum beta-human chorionic gonadotropin (hCG) levels was similar in both groups, although in the linear salpingostomy group the decrease was immediate. No difference in tubal patency on follow-up hysterosalpingography was observed between the two groups. CONCLUSIONS: Although this is a preliminary report with a small number of patients, both types of treatment were safe and effective. An advantage of linear salpingostomy was the predictable and consistent decline of circulating beta-hCG, and consequently a reduced need for a close follow-up. Local MTX injection was safe, economic, effective, and easy to perform, and in our experience the surgical time was statistically shorter than that for linear salpingostomy. Therefore, in selected patients, local injection of MTX could be the treatment of choice for unruptured ectopic pregnancy, avoiding a longer and potentially more dangerous procedure. Long-term outcomes do not seem to differ between the two types of treatment
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